a sudden, brief event (often a loud noise or a figure appearing) in a film, game, or other media designed to startle the audience.

映画・ゲームなどで観客を驚かせるための、短く突然の（大きな音や姿の出現などの）演出

to cause someone to be startled by using a jump-scare.

（ジャンプスケアで）人を驚かせる